Kinda busy, but I'll throw my 2 cents in: term limits are great, but only for the politicians you don't like. There are a few congressmen I am genuinely grateful are continually reelected, Russ Feingold in particular, and they would mostly be out if term limits were applied (though maybe not if they're as long as you say). It's probably true that lame duck politicians are bolder and more willing to vote their conscience, but two problems leap to mind. First: Jim Bunning, not seeking reelection, recently held up benefits to people who really needed them, and probably wouldn't have if he weren't a lame duck. Politicians voting their conscience is only good when they have one. Second, term limits may have the perverse effect of exacerbating the problem of politicians voting for their corporate buddies, because now every congressperson is going to be angling for a cushy job in a few years, and you can bet they have dollar signs on the brain.
From a formal standpoint, term limits are undemocratic (and state-imposed term limits on congressmen are actually unconstitutional, though that could change). They deny the people the opportunity to vote people into office that they might want to. It's not necessarily a bad thing to have a government that is less democratic; we allow congress to "punish its Members for disorderly Behavior, and, with the Concurrence of two thirds, expel a Member," after all, whether the people of a state want them in or not. (Rare, but it happens every once in a while, mostly for corruption.)
